Fix “Microsoft Account logins are not supported” error in Microsoft Teams on Mac

Logo for Microsoft Teams: A "T" in a blue square ahead of stylized light blue and dark blue icons for two people (heads and torsos)

I started my day this morning with an early online meeting in Microsoft Teams.

Teams is one of the less common platforms for me to deal with, but luckily when I was invited on Friday, I did have the forethought to test it out. My main workstation is a MacBook, and I am more used to Google Meet and Zoom Workplace. Especially from Zoom during the pandemic I know all too well the need to regularly open the application just to “Check for updates…” I also learned in pays to get into Zoom early before any meeting to allow time to go into “Settings…” and check the Audio panel to “Test speaker” and “Test mic.”

So anyway, I got the invite about this MS Teams meeting on Friday, and went in to the app to be sure it was up to date and checked settings and permissions. In the process I was prompted to log in. I know I’ve used my email address for that before, so I tried to use it to log in. Error:

AADSTS90023: Microsoft Account logins are not supported.

That seems weird. Why wouldn’t Microsoft support a Microsoft Account as a way to log in to a Microsoft Product?

I do some checking.

I find this report of the error on Microsoft Learn: “Teams Mac – Constant inability to sign in to the system.” The “Accepted answer” suggests first checking and updating the Teams client. Great, aleady did that. Then it suggest using the web version of Teams instead. Okay, if I have to, but I’d really like to get the Teams program itself working on my Mac. (For what it’s worth, I’ve got Microsoft Teams Version 24335.207.3345.5574 (24335.207.3345.5574) on a MacBook Air (M1, 2020) running macOS Sequoia 15.2 (24C101).) I go to step three to try, and this one sounds promising:

Clear the Teams cache from your device.

I do some looking for how to clear the cache. No luck. As is correctly pointed out in the comments on the “Accepted answer” re: clearing the cache, “all instructions tell me to open Teams and go into the Privacy section of Settings and instruct the cache removal. On the Mac version, there is no cache removal option.”

I do some digging. I find in the Microsoft Support Community: “Clearing Cache in “New” Teams for Mac.” This gives the apparently old cache location of Microsoft Teams, in:

~/Library/Application Support/Microsoft

(Via Command+Shift+G from the Finder, or using the Terminal to get there.) It also gives the apparently old way of clearing the cache from there, simply:

Delete the Teams folder.

I make sure Microsoft Teams is not running, check and see that the Teams folder is there in ~/Library/Application Support/Microsoft — and I delete it.

I launch the Microsoft Teams application, and this time it does let me log in using the same email address it had given me the “AADSTS90023: Microsoft Account logins are not supported.” error for before.

Problem fixed!

(This blog post expands on my quick Bluesky thread from Friday going through the fix.)

Hoping this helps somebody else!